Site and soil conditions
Camellias are woodland plants that grow best in shelter and light shade, although with careful watering they can be grown in sunny positions.
They prefer free-draining conditions, with plenty of organic matter, such as leaf mould, incorporated into the soil.
Being ericaceous plants, camellias require an acid soil. If your soil isn't acid then consider growing your camellia in a container.
Tap water, especially in hard water districts, often contains too much calcium for camellias, reducing the acidity around the roots over time. Rain water is ideal for watering camellias. If rain water runs out, tap water is satisfactory for a month or two in summer.
Feed camellias with acidic fertilisers, such as Chempak Ericaceous, Miracle-gro Ericaceous, sulphate of ammonia or sulphate of potash. Controlled release fertiliser pellets are available from Miracid and Phostrogen to mix into the potting compost of container-grown plants, avoiding the need for further feeding until the following season.
You can use organic-based fertilisers, including seaweed products and fish, blood and bone. It should be noted, however, that fish, blood and bone is mildly alkaline (because of the calcium in the bone) so it would be best not to use where the soil is pH of 7 or above (neutral to alkaline) as this could encourage deficiencies such as chlorosis. To be clear, though, annual applications are unlikely to cause much problem and, where the pH is increased, the soil could be acidified to compensate for applying this useful fertiliser.
Camellias make lovely container-grown plants and this is a particularly good method if your garden soil is too alkaline for camellias. Use an ericaceous or multi-purpose potting compost. John Innes ericaceous compost usually gives good results, as its loam content makes it especially easy to manage.
RHS research has found that soil-less potting media, including peat-free potting composts, are suitable for camellia growing. However these composts can lose their structure over time leading to poor drainage and an airless root environment, causing leaves to brown and die back. Re-potting every other year into fresh potting compost is recommended. In the intervening year, replace the top 5cm (2in) of compost. You can re-pot back into the same pot if you trim off up to a third of the roots to make room for fresh potting compost.